Method of producing a woven webbing

ABSTRACT

Disclosed is a method for the production of a planar textile structure, especially a woven belt band, especially for safety belts in motor vehicles, consisting of warp threads and at least one weft thread. The method is characterized in that at least one hybrid multi-filament thread, made up of at least first and second filaments, is used for weaving, said second filaments having a higher melting point than the first filaments. Flexible elliptical and flat interlacing points are formed during shed closing of the warp threads, and the belt band is thermofixed after weaving, whereby the first filaments melt and the second filaments of the multifilament yarn are at least partially glued together.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of PCT/EP2003/012151, filed Oct. 31,2003, which claims priority to German Application No. 102 55 360.2,filed Nov. 27, 2002; both of which are incorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a method of producing a textile sheet fabric,particularly a woven webbing, more particularly a vehicle occupantrestraint belt, comprising warp threads and at least one weft thread.

A wide variety of methods of producing such webbing and their attendantdisadvantages are known. As a rule, the warp threads thereof consist ofmultifil yarns whereas for the weft thread(s) multi- or monofil yarnsare employed singly or in combination. Whilst making a webbingexclusively of multifil yarn for the weft thread material has thedisadvantage of it having practically no CD stiffness and elasticity,webbing with weft threads of monofil material although featuring thedesired CD and elasticity, suffer the disadvantage that after a certainnumber of chaffing actions the monofil weft threads at the edges wherethe weft returns, juts from the belt in forming a hard sawtooth-likewoven edge damaging to the clothing of the vehicle occupant or evencausing injury to the chest and neck of the occupant. By comparison,webbing made of monofil weft material is thick as compared to webbingmade exclusively of multifil material.

The invention is based on the object of proposing a method for producinga woven webbing which eliminates, or at least greatly reduces, thedisadvantages known from prior art. This object is achieved by a methodas it reads from claim 1. This method has the advantage thatincorporating the hybrid multifil yarn in the weft now makes it possibleto achieve the positive structures of the keying points in the woven.

DETAILED DESCRIPTION

The hybrid multifil yarn comprises at least first and second filaments.This yarn simply termed “hybrid yarn” hereinafter is wefted in formingflexible elliptical and low profile keying points in shed closure of thewarp threads, as is unattainable with monfil yarns. In setting, afterweaving, the multifil yarn in accordance with the invention is heated toabove the melting point of the low-melting filaments. It is this meltingof the low-melting filaments that results in the high-melting filamentsof the multifil yarn interbonding at least in part so that the multifilyarn is or can also be bonded as a whole or preferably its outlyingfilaments in addition to the keying points with the intersecting warpthreads in thus achieving the high CD consolidation of the webbing. Theprocess as described for modifying the mechanical properties—inachieving the description CD stiffness and elasticity—is done with thethreads ondulated, i.e. the thickness of the woven webbing is thinnerand the webbing surface formed by the warp threads is smoother becausethe heads of the keying points are configured less prominent.

As already indicated above, producing a webbing in accordance with theinvention results in a elliptical low-profile, soft weft reversal in theregion of the edges, because of the multifil yarn structure. Now,abrasion of the selvedge no longer results in the feared sawtooth effectand its negative consequences as in prior art from damage to the edgesof the webbing.

In one aspect of the method in accordance with the invention polyamideis used for the first filaments and polyester for the second filaments,resulting in an optimum harmonizing pairing of the materials in thewebbing. In another advantageous aspect of the invention polyester isused for both the first and second filaments in the hybrid multithreadof the weft thread. This has the additional major advantage of thematerial permitting better recycling. Advantageously the first filamentsin this case are made of a modified polyester.

Thermally treating the hybrid yarn textile sheet fabric at approximately220° C. by the method in accordance with the invention results in theindividual second filaments interbonding so that in the weft thread amonofil-type yarn body is achieved having the mechanical properties(resiliency, low fluffiness, stiffness) of a monofil yarn in thuscombining all positive features of multifil yarn and monofil yarn in themethod in accordance with the invention and the resulting product.

The method in accordance with the invention is applicable, of course, toall known types of webbing, the achievable advantages of which for thefirst time now combine low thickness of the webbing, smoother surfacethereof, soft reversals in the region of the edges, resiliency, CDstiffness and perfect surface quality. Advantageously, multifil yarnsare employed as the weft thread, the mass ratio of first filaments tosecond filaments being in the range of approximately 20%-90% toapproximately 10%-80%.

1. A method of producing a textile sheet fabric, particularly a wovenwebbing, more particularly a vehicle occupant restraint belt, comprisingwarp threads and at least one weft thread comprising the steps of:weaving at least one hybrid multifil yarn as the weft thread composed ofat least first and second filaments, the second filaments having amelting point higher than that of the first filaments, forming flexibleelliptical low-profile keying points in the shedding closure of the warpthreads, and thermosetting the webbing after weaving, the firstfilaments melting and the second filaments of the multifil yarninterbonding at least in part.
 2. The method as set forth in claim 1,wherein polyamide is employed for the first filaments and polyester forthe second filaments.
 3. The method as set forth in claim 1, whereinpolyester is employed for the first filaments and for the secondfilaments.
 4. The method as set forth in claim 1, wherein the mass ratioof first filaments to second filaments is in the range of approximately20%-90% to approximately 10%-80%.
 5. The method as set forth in claim 1,wherein the at least one weft thread is woven only over part of the warpthreads and a second weft thread shedded with the at least one warpthread, but running over the full width of the webbing.
 6. The method asset forth in claim 1, wherein the webbing is woven with round selvedge.7. The method as set forth in claim 1, wherein the webbing is providedin the region of its edges with additional threads.
 8. The method as setforth in claim 1, wherein at least one of the warp threads is meshed atone or both edges with tucking and/or locking threads.
 9. The method asset forth in claim 1, wherein the textile sheet fabric is woven withdiffering warp threads.